The proposed investigations continue a research effort that began in 1983 and has been supported by three grants from the NIH. A tissue culture model of nerve cell injury where techniques of laser cell surgery were used to effect neurite transection lesions in individual mammalian spinal cord (SC) neurons was used to evaluate treatment strategies for the physical (membrane disruption) trauma of acute phase spinal cord injury (SCI). A central goal has been to demonstrate the potential of the in vitro investigative approach for the study of questions relevant to in vivo CNS trauma. Three observations made in the course of these evaluations form the basis for the continuation proposal: (1) that inhibition of protein synthesis increases survival of lesioned neurons from approximately 50% to 80%, (2) that barbiturates increase survival from 50% to 70%, and (3) that controlled cooling (17 degrees C for 2h) increases survival from 50% to 70%. The significant protection by these interventions is in contrast to the modest protection of lesioned neurons by methylprednisolone (Rosenberg-Schaffer and Lucas, 1993) which is currently the treatment modality of choice for SCI. The first set of specific aims (Section I) will test three hypotheses: (1) that a significant proportion of the neuronal death that occurs after neurite transection is a type of "programmed" cell death, (2) that survival or death is correlated with the synthesis of specific messenger RNA's and/or proteins associated with injury and morbidity, and (3) that residual electrical activity contributes to death after dendrotomy. The last aim (Section II) to perform an extensive dose-response evaluation of the ability of GM1 ganglioside to protect neurons after dendrotomy, continues our in vitro evaluations of promising, experimental clinical treatments for acute phase SCI. Because GM1 has been reported to abolish protection by methylprednisolone, we will also compare the combination of GM1 and methylprednisolone to the individual treatments. The first set of specific aims will provide information about the molecular mechanisms underlying traumatic neuronal death, and may elucidate new strategies for the treatment of acute phase SCI. Fulfillment of the last specific aim will provide much-needed information relevant to the efficacy of GM1 as an acute phase treatment for the primary mechanical trauma of SCI, the optimum "dosage" and time for initiation of treatment, and the efficacy of GM1 combined with methylprednisolone. The combined expertise of the members of the research team will be utilized for the systematic survival, ultrastructural, molecular, and electrophysiological evaluations required for fulfillment of the specific aims.